Pipe or plumbing systems often include access openings or ports that allow the interior of the pipes of the pipe system to be inspected and/or cleaned. Access opening configurations for such pipe systems can vary in size and shape, although many configurations are standardized. In one common configuration, an access opening (often referred to as a “clean-out”) is provided at the end of a relatively short section of cylindrical pipe that extends away from the axis of the main pipe section. Clean-outs may extend from a main pipe section at any angle. Those that extend approximately 90 degrees from the main pipe section are commonly called “clean-out tees” (referring to the T-shape created by the intersecting pipe sections). Other access openings include, but are not limited to, roof vents, storm drains, closet bends, and pipe ends.
Access openings may also be used to test the integrity of the pipe system. Currently, this is accomplished by placing temporary test plugs in the clean-outs or other openings of the pipe system. A test media such as water or air is then introduced into the pipe system for a period of time to determine if there are any leaks. After successful testing, the test plugs are removed. Test plugs can generally be categorized into mechanical test plugs and pneumatic test plugs. Existing mechanical test plugs typically include devices that seal pipe systems via mechanical activation, such as by turning a threaded connection member to expand an elastomeric ring that seals an inner surface of a pipe section. Existing pneumatic test plugs include elongate elastomeric bladders that are attached directly to an air source. The bladders are inserted into the pipe system through the clean-outs or other access openings and are then inflated to seal the pipe section. After testing, the test plugs are deflated or deactivated and then removed from the pipe system.
Although some existing pneumatic test plugs may display a maximum inflation pressure on the outside of the bladder, this does not provide protection for overinflation, but instead relies on the diligence of the operator and the existence and accuracy of an air inlet pressure gauge. If the elastomeric bladders of such pneumatic test plugs were to be overinflated, problems could occur. These problems may include damage to the test plug, damage to the pipe system, and/or other inconveniences for the operator. A proposed solution to this problem involves using an external pressure regulator or external pressure relief device on the air inlet, but these solutions are cumbersome and are often ignored by operators. They also increase the time required to inflate the bladder. Additionally, many pressure regulators must be set before inflation begins, and regulation settings may differ for pipes having different internal diameters.
Other existing pneumatic test plugs include integrated pressure relief devices; however, the present inventors have found that these particular pressure relief devices tend to leak, do not provide repeatable results, and may disrupt testing of the pipe system. Specifically, some pneumatic test plugs include relief valves that have mechanical springs and seals; other pneumatic test plugs include relief valves that are positioned on the backside of the elastomeric bladder. The present inventors have found that pneumatic test plugs employing the former pressure relief devices may be prone to fouling and tend to collect contamination, thus negatively affecting their performance. Similarly, the present inventors have found that pneumatic test plugs employing the latter pressure relief devices may release excess air into the enclosed area of the pipe system behind the test plug, thus tending to force the test plug out of the clean-out access area and disrupting the test.
As a result, there is a need for an improved pneumatic test plug for use with a pipe section having a generally cylindrical internal pipe wall. The pneumatic test plug should be easy to use and should not require the operator to make additional settings or readings. It should be reliable, provide repeatable results, and it should not require additional external equipment or otherwise disrupt testing of the pipe system.